First high-resolution analysis of phosgene 35cl2co and 35cl37clco fundamentals in the 250 - 480 cm−1spectral region

Phosgene (\chem{COCl_2}) is relatively more abundant in the stratosphere, but is also present in the troposphere in spite of a shorter lifetime (seventy days). Monitoring its concentration by remote sounding of the upper atmosphere is of importance, since some of its strong infrared absorptions, occurring in the important 8-12 $\mu$m atmospheric window, hinder the correct retrieval of Freon-11 concentration profiles\footnote{G. Toon, J.F. Blavier, B. Sen and B.J. Drouin, Geophys. Res. Lett., 28/14 (2001) 2835.}. Indeed, the infrared absorptions used to retrieve this ozone depleting compound occur in the same spectral region. Phosgene, presents two fundamental bands in the 250 - 480 \wn spectral region, with the lowest ($\nu_3$) near 285 \wn. These are responsible for hot bands, not yet analysed but of great importance for accurate modeling of the 5.47 $\mu$m ($\nu_1$) and 11.75 $\mu$m ($\nu_5$) spectral regions and consequently the correct retrieval of Freon-11 atmospheric absorption profiles. High-resolution absorption spectra of phosgene have been recorded at 0.00102 \wn resolution in the 250–480 \wn region by Fourier transform spectroscopy at synchrotron SOLEIL. Due to the spectral congestion, the spectra have been recorded at low temperature (197 K) using a 93.15 m optical path length cryogenic cell\footnote{F. Kwabia Tchana, F. Willaert, X. Landsheere, J.-M. Flaud, L. Lago, M. Chapuis, P. Roy and L. Manceron, Rev. Sci. Inst., 84 (2013) 093101.}. This enables the first detailed far-infrared analyzes of the $\nu_3$ and $\nu_6$ bands of the $^{35}$Cl$_{2}$CO and $^{35}$Cl$^{37}$ClCO isotopologues of phosgene. Using a Watson-type Hamiltonian, it was possible to reproduce the upper state rovibrational infrared energy levels to within the experimental accuracy. The results will be presented in this talk

HIGH-RESOLUTION ANALYSIS OF THE 83.3 μm TORSIONAL BANDS OF THE ClONO2 MOLECULE

Chlorine nitrate (\chem{ClONO_2}) is a very important atmospheric "reservoir" of ClO and \chem{NO_2}, destroying stratospheric ozone through catalytic cycles\footnote{P. J. Crutzen, \textit{Quart. J. Royal Met. Soc.} \textbf{96}, 320 (1970); M. J. Molina and F. S. Rowland, \textit{Nature} \textbf{249}, 810 (1974).}. It was detected for the first time by infrared (IR) spectroscopy\footnote{D. G. Murcray \textit{et al.}, \textit{Geophys. Res. Lett.} \textbf{6}, 857 (1979).}, a detection confirmed and extended by the MIPAS\footnote{H. Fischer \textit{et al.}, \textit{Atmos. Chem. Phys.} \textbf{8}, 2151 (2008).} and the ATMOS satellite experiments\footnote{R. Zander \textit{et al.}, \textit{Geophys. Res. Lett.} \textbf{13}, 757 (1986).}. Many high-resolution microwave and mid-IR spectroscopy studies of \chem{ClONO_2} have been published\footnote{J. Orphal, M. Birk, G. Wagner, and J.-M. Flaud, \textit{Chem. Phys. Lett.} \textbf{690}, 82 (2017).}. However, \chem{ClONO_2} presents 4 fundamentals in the far-IR region below 600 \wn, with the lowest one corresponding to the torsional mode \nub{9} around 83.3 $\mu$m. This band has been observed at low resolution\footnote{J. W. Fleming, \textit{Infrared Phys.} \textbf{18}, 791 (1978); K. V. Chance and W. A. Traub, \textit{J. Mol. Spectrosc.} \textbf{95}, 306 (1982).} but without precise determination of the band center. More recently, the analysis of the mid-IR \nub{8} and \nub{8} + \nub{9} band spectral regions of $^{35}$\chem{ClONO_2} allowed the indirect but accurate determination of the \nub{9} band center\footnote{J.-M. Flaud, W. J. Lafferty, J. Orphal, M. Birk, and G. Wagner, \textit{Mol. Phys.} \textbf{101}, 1527 (2003).}. In this work, the 83.3 $\mu$m region of \chem{ClONO_2} has been recorded at high resolution (0.001 \wn) using a Fourier transform spectrometer and the SOLEIL synchrotron light source. The spectrum corresponds to the absorption of the torsional mode, \nub{9} around 123 \wn and a series of \textit{n}\nub{9}-(\textit{n}-1)\nub{9} hot bands. In this talk, the analysis of the \nub{9} bands of $^{35}$\chem{ClONO_2} and $^{37}$\chem{ClONO_2} and 2\nub{9}-\nub{9} band of $^{35}$\chem{ClONO_2} will be presented. In turn, this will enable an analysis of the hot bands involving low energy levels in the mid-IR region where \chem{ClONO_2} is detected and modelled

Gas phase dicyanoacetylene (C4N2) on Titan: New experimental and theoretical spectroscopy results applied to Cassini CIRS data

International audienceDicyanoacetylene has not been observed so far in the gas phase in Titan’s atmosphere but this molecule is still on the list of the detected species, on the basis of the correspondence between a solid phase feature measured at 478 cm−1 in the laboratory and a spectral feature observed by Voyager. In this work, the infrared spectrum of gaseous C4N2 has been investigated to improve our knowledge of the band intensities and the line parameters for this molecule. Results of previously investigated bands have been revised and the intensity of the ν9 band at 107 cm−1, measured for the first time, was found to be the strongest absorption in the whole infrared domain. We have also improved the analysis of the complex rotational and hot band structure of C4N2 in order to obtain the first line lists for both bending modes ν8 and ν9. Using our radiative transfer code including the new line list of the strong ν9 band, we have searched for the signature of C4N2 at 107 cm−1 in the atmosphere of Titan utilizing Titan CIRS far infrared spectra. Despite averaging a large number of CIRS spectra at northern latitudes during the very favorable Titan winter, no gaseous C4N2 could be detected. At the 1-σ level we obtain an abundance upper limit of 5.3 × 10−10 for the limb average which is lower than or comparable to previously inferred values. As a consequence, the absence or very low amount of gaseous C4N2 makes quite puzzling its presence in the solid phase with an abundance compatible with the observed spectral feature at 478 cm−

The 2009 edition of the GEISA spectroscopic database

The updated 2009 edition of the spectroscopic database GEISA (Gestionet Etudedes Informations Spectroscopiques Atmospheriques ; Management and Study of Atmospheric Spectroscopic Information) is described in this paper. GEISA is a computer-accessible system comprising three independent sub-databases devoted, respectively, to: line parameters, infrared and ultraviolet/visible absorption cross-sections, microphysical and optical properties of atmospheric aerosols. In this edition, 50 molecules are involved in the line parameters sub-database, including 111 isotopologues, for a total of 3,807,997 entries, in the spectral range from 10-6 to 35,877.031cm-1. GEISA, continuously developed and maintained at LMD (Laboratoirede Meteorologie Dynamique, France) since 1976, is implemented on the IPSL/CNRS(France) ‘‘Ether’’ Products and Services Centre WEB site (http://ether.ipsl.jussieu.fr), where all archived spectroscopic data can be handled through general and user friendly associated managements of software facilities. More than 350 researchers are registered for online use of GEISA

The HITRAN2020 Molecular Spectroscopic Database

The HITRAN database is a compilation of molecular spectroscopic parameters. It was established in the early 1970s and is used by various computer codes to predict and simulate the transmission and emission of light in gaseous media (with an emphasis on terrestrial and planetary atmospheres). The HITRAN compilation is composed of five major components: the line-by-line spectroscopic parameters required for high-resolution radiative-transfer codes, experimental infrared absorption cross-sections (for molecules where it is not yet feasible for representation in a line-by-line form), collision-induced absorption data, aerosol indices of refraction, and general tables (including partition sums) that apply globally to the data. This paper describes the contents of the 2020 quadrennial edition of HITRAN. The HITRAN2020 edition takes advantage of recent experimental and theoretical data that were meticulously validated, in particular, against laboratory and atmospheric spectra. The new edition replaces the previous HITRAN edition of 2016 (including its updates during the intervening years). All five components of HITRAN have undergone major updates. In particular, the extent of the updates in the HITRAN2020 edition range from updating a few lines of specific molecules to complete replacements of the lists, and also the introduction of additional isotopologues and new (to HITRAN) molecules: SO, CH3F, GeH4, CS2, CH3I and NF3. Many new vibrational bands were added, extending the spectral coverage and completeness of the line lists. Also, the accuracy of the parameters for major atmospheric absorbers has been increased substantially, often featuring sub-percent uncertainties. Broadening parameters associated with the ambient pressure of water vapor were introduced to HITRAN for the first time and are now available for several molecules. The HITRAN2020 edition continues to take advantage of the relational structure and efficient interface available at www.hitran.org and the HITRAN Application Programming Interface (HAPI). The functionality of both tools has been extended for the new edition

The HITRAN2020 molecular spectroscopic database

The HITRAN database is a compilation of molecular spectroscopic parameters. It was established in the early 1970s and is used by various computer codes to predict and simulate the transmission and emission of light in gaseous media (with an emphasis on terrestrial and planetary atmospheres). The HITRAN compilation is composed of five major components: the line-by-line spectroscopic parameters required for high-resolution radiative-transfer codes, experimental infrared absorption cross-sections (for molecules where it is not yet feasible for representation in a line-by-line form), collision-induced absorption data, aerosol indices of refraction, and general tables (including partition sums) that apply globally to the data. This paper describes the contents of the 2020 quadrennial edition of HITRAN. The HITRAN2020 edition takes advantage of recent experimental and theoretical data that were meticulously validated, in particular, against laboratory and atmospheric spectra. The new edition replaces the previous HITRAN edition of 2016 (including its updates during the intervening years). All five components of HITRAN have undergone major updates. In particular, the extent of the updates in the HITRAN2020 edition range from updating a few lines of specific molecules to complete replacements of the lists, and also the introduction of additional isotopologues and new (to HITRAN) molecules: SO, CH3F, GeH4, CS2, CH3I and NF3. Many new vibrational bands were added, extending the spectral coverage and completeness of the line lists. Also, the accuracy of the parameters for major atmospheric absorbers has been increased substantially, often featuring sub-percent uncertainties. Broadening parameters associated with the ambient pressure of water vapor were introduced to HITRAN for the first time and are now available for several molecules. The HITRAN2020 edition continues to take advantage of the relational structure and efficient interface available at www.hitran.org and the HITRAN Application Programming Interface (HAPI). The functionality of both tools has been extended for the new edition

Study of the Rotational Structure of the v2 Inversion Band of the 15NH2D Molecule

International audienc

ABSOLUTE LINE INTENSITIES OF H2_{2}CO IN THE 3.5 AND 5.7-μ\mum REGIONS

Author Institution: Universite Pierre et Marie Curie-Paris 6; CNRS; Laboratoire de Dynamique, Interactions et Reactivite, UMR 7075, Case Courrier 49, 4 Place Jussieu, 75252 Paris Cedex 05, France; Laboratoire Inter Universitaire des Systemes Atmospheriques (LISA), CNRS, Universites Paris 12 et 7, 61 Avenue du General de Gaulle, 94010 Creteil Cedex, FranceFormaldehyde (H$_{2}$CO) is detected in the earth's troposphere by infrared techniques in the 3.5 and 5.7-$\mu$m regions. Recent measurements produced line positions and relative line intensities}, \textbf{221}, (2003) 192. A. Perrin, A. Valentin, and L. Daumont, \textit{J. Mol. Struct.}, \textbf{780-781}, (2006) 28.} and also IR$\Leftrightarrow$UV line intensity intercomparisons }, in press, (2007).}. For atmospheric retrievals absolute intensities and line broadening parameters are needed. For that, new Fourier transform spectra were recorded at high resolution (0.0035 cm$^{-1}$) at LADIR in the 1600-3000 cm$^{-1}$ spectral region. Low pressures (up to 0.5 torr) of H$_{2}$CO were generated by warming paraformaldehyde. An appropriate monitoring of the heating temperature ($\approx$ 40$^{irc}$ C) avoided any polymerization and allowed to obtained a stable pressure of pure H$_{2}$CO (98 $\pm$ 1\%). In this way accurate line positions and absolute intensities of H$_{2}$CO were measured and theoretical modelled in the 3.5 and 5.7-$\mu$m regions leading also to an intercomparison of intensities between the two spectral regions. The determination of self- and N$_{2}$-broadening coefficients is in progress

New line positions analysis of the 2 ν 1 and ν 1 + ν 3 bands of NO 2 at 3637.848 and 2906.070 cm −1

International audienc

Raman and infrared spectra of the ν1 band of oxirane

4 pags. ; 3 figs. ; 1 tab.Fourier transform spectra of oxirane [ethylene oxide (c-C2H4O)] have been recorded in the 3.17 μm–3.50 μm region with a resolution of 0.005 cm−1. In addition, a Raman spectrum covering the same spectral region was recorded at a resolution of 0.44 cm−1. Using the Raman spectrum, it was possible to determine the band centre of the ν1 band to within 0.5 cm−1. This determination was essential to assign the infrared region transitions of the B-type ν1 band since this weak band is masked by the much stronger A-type bands ν2 + ν10 and ν9 and ν13 C-type band. Using a Watson-type Hamiltonian for an asymmetric-top molecule, it was possible to reproduce the observed energy levels to within 2 × 10−3 cm−1 and the Raman spectrum could be satisfactorily modelled. The band centre was determined to be ν0 (ν1) = 3018.3454(10) cm−1 (1 σ uncertainty. c 2013 Taylor & FrancisThis work has been partially supported by the Spanish Ministerio de Ciencia e Innovaci´on through Grant FIS2010-22064-C02.Peer reviewe